FIG. 18 is a block diagram showing a conventional signature verification system. FIG. 19 is a block diagram showing the interior of a signature input apparatus constituting the signature verification system. As understood from FIGS. 18 and 19, the conventional signature verification system includes a signature input apparatus 100 and a signature verifying apparatus 106, and signature input apparatus 100 and signature verifying apparatus 106 are connected through a controller 103.
In signature input apparatus 100, a transparent, active type liquid crystal display unit 101 is mounted on the top of a coordinate input unit 102. This active type liquid crystal display unit 101 incorporates a reduced thickness-type backlight 113 and a backlight power source 114. A signature which has been written on a display area 107 of active type liquid crystal display unit 101 by a particular writer, using a dedicated pen 105 is transferred to a coordinate input area 115 in coordinate input unit 102, where the handwriting of the signature is read out, specifically, the X-coordinate and Y-coordinate and its writing pressure are detected by an X-axis driver circuit 116 and a Y-axis driver circuit 117, a transmission/reception circuit 118 and a CPU 119.
As stated above, the handwriting coordinate information and writing pressure data detected by coordinate input unit 102 are transferred to signature verifying apparatus 106 by way of controller 103, then therein, are used for signature registration and signature verification. At the same time, the data is used for the calculation of the handwriting coordinates in controller 103, the result being sent out to active type liquid crystal display unit 101 as its display data. Based on the transferred display data to liquid crystal display unit 101, the handwriting of the signature is displayed on display area 107 via display controller 111, memory 110, X-axis driver circuit 108 and Y-axis driver circuit 109.
By repeating the above cycle of operations quickly, the handwriting of the signature is displayed as a liquid crystal representation on display area 107 as if it were being written on a paper surface by a writing implement. Here, the active type liquid crystal display is one which displays characters and/or patterns etc., by optically changing, by providing an electric field or the like, the state of arbitrary dots inside the display dots which are arrayed matrix-wise on a plane defined by the X-axis and Y-axis. Signature input apparatus 100 may incorporate a character generator 112 for character fonts for displaying type characters.
On the other hand, sent out from signature verifying apparatus 106 are instructions such as the start of input of a signature (input start of coordinate input unit 102), transfer of the handwriting coordinate data to active type liquid crystal display unit 101, the end of input of a signature, and display deletion of active type liquid crystal display unit 101. Since signature input apparatus 100 incorporates a voice guidance unit 104 composed of an amplifier 121 and a speaker 120 for performing voice guidance, the operation can be guided not only by the liquid crystal display but also by voice guidance.
However, active-type liquid crystal display unit 101 used in a signature input apparatus 100 of the conventional type, has the following problems, as compared to an externally charged type liquid crystal sheet for displaying a signature as a liquid crystal representation by externally applying a static charge.
A) The active type liquid crystal display unit uses a feedback configuration of the coordinate position, needing additional arithmetic operations, so that the response speed to the coordinate input is slower even if the processing capacity is equal. PA1 B) The active type liquid crystal display unit needs active elements for liquid crystal driving, and hence the liquid crystal-display itself needs a complicated structure and costs more. PA1 C) The active type liquid crystal display unit tends to be thick, so it lacks flexibility. PA1 D) The active type liquid crystal display unit uses a dot representation, so the smoothness of the contours of the characters of the signature lowers. PA1 E) When the active type liquid crystal display unit has broken down, it is very difficult to replace its liquid crystal display portion. PA1 F) In the active type liquid crystal display unit, some adjustment is needed so as to avoid the display coordinate positions deviating from the input coordinate positions. PA1 G) In the active type liquid crystal display unit, the user cannot have a normal writing sensation such as when paper and a pencil are used. PA1 H) The active type liquid crystal display unit needs a deleting operation such as data rewrite etc., for canceling the handwriting of a signature after the liquid crystal display of the signature.
The present invention has been devised in order to solve the above conventional problems, and it is therefore an object of the invention to provide a signature input apparatus and a signature verification system including the same, wherein a liquid crystal representation of a signature can be performed by applying static charge, to allow the handwriting coordinate information of the signature to be detected and the characters of the signature to disappear by themselves.